package com.chen.pc;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class PC_lock {
    public static void main(String[] args) {
        Data2 data = new Data2();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "A").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "B").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "C").start();

        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "D").start();

    }
}

// 判断等待、业务、通知
class Data2 {
    private int number = 0;

    // 创建锁
    Lock lock = new ReentrantLock();
    // 利用lock创建condition
    Condition condition = lock.newCondition();

    // +1
    public void increment() throws InterruptedException {

        lock.lock();
        try {
            // 适用while语句判断是否需要等待，防止虚假唤醒问题
            while (number != 0) {
                // 等待
                condition.await();
            }
            // 业务
            number++;
            System.out.println(Thread.currentThread().getName() + "=>" + number);
            // 通知其它线程，+1已经完成
            condition.signalAll();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }

    }

    // -1
    public void decrement() throws InterruptedException {

        lock.lock();
        try {
            while (number != 1) {
                // 等待
                condition.await();
            }
            number--;
            System.out.println(Thread.currentThread().getName() + "=>" + number);
            // 通知其它线程，-1已经完成
            condition.signalAll();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}
